Plastic closures for containers typically comprise a circular base having an integral peripheral skirt with internal threads for engaging external threads on the container finish. A liner is assembled to the closure at the closure base for sealing engagement with the annular top surface of the container surrounding the container mouth. The liner may be adhesively secured to the base of the closure, or may be press fitted into the closure and retained against the closure base by a bead or other suitable means on the inside diameter of the skirt adjacent to the base. For some products such as vitamins or instant coffee, a glassine liner seal is incorporated as part of the liner. This glassine inner seal may be used as a tamper-evident feature. The liner preferably has a base of vinyl-impregnated laminated pulp construction, a liner membrane of glassine paper construction, and a thermoplastic adhesive such as wax or butyl rubber securing the liner membrane to the base. These liners are typically made in long strips and then die cut to the appropriate diameter for assembly to the closure. In applications in which the liner is press fitted into the closure over the closure internal threads and/or liner-retaining bead, the periphery of the liner membrane can become separated from the liner base. This separation can be exacerbated to the point that the liner membrane curls and peals from the base, particularly when the lined closure is subjected to humidity cycles (such as during shipment) before the closure is applied to a container. Such curling and pealing is unsightly, and can ultimately result in the glassine membrane falling out of the closure.
It is therefore a general object of the present invention to provide a method and apparatus for assembling a liner to a closure in which the liner membrane is resecured to the liner base during or after the assembly operation to ensure proper sealing with the container finish during use. Another object of the present invention is to provide a method and apparatus of the described character that can be readily implemented in an otherwise conventional assembly operation with minimum additional tooling investment, and with little or no reduction in assembly productivity.